The use of hollow monofilaments in connection with reverse osmosis and other separation and purification procedures is old and well known as shown in McLain U.S. Pat. No. 3,422,008, issued Jan. 14, 1969, to Dow Chemical Company, and as shown in report PB233,102 of the Monsanto Research Corporation, dated September, 1973, to the U.S. Department of the Interior.
A variety of methods is known to prepare the filament bundle assemblage. Many of these are intricate and many involve complex steps of winding with special machinery and utilization of porous sheets which act as support members.
In a module, a properly assembled multifilament array must meet a number of specifications. Among these is a geometric arrangement which provides a fairly high packing density and which at the same time minimizes channeling of the feed fluid as it passes among the filaments. Therefore, some method of keeping filaments from packing densely in certain areas and loosely in others is desirable. In other words, packing density of the filament array should be both very uniform and in the order of about 25 to 60%, if some of the main advantages of the use of hollow filaments are to be achieved. In view of these considerations the use of various filament assembly techniques is frequently unattractive.